Bioluminescent imaging of Cdk2 inhibition in vivo

Guo-Jun Zhang, Michal Safran, Wenyi Wei, Erik Sorensen, Peter Lassota, Nikolai Zhelev, Donna S. Neuberg, Geoffrey Shapiro, William G. Kaelin Jr

    Research output: Contribution to journalArticlepeer-review

    89 Citations (Scopus)


    Many proteins and pathways of pharmaceutical interest impinge on ubiquitin ligases or their substrates. The cyclin-dependent kinase (Cdk) inhibitor p27, for example, is polyubiquitylated in a cell cycle−dependent manner by a ubiquitin ligase complex containing the F-box protein Skp2. Regulated turnover of p27 is due, at least partly, to its phosphorylation by Cdk2 on threonine 187, which generates a Skp2-binding site. We made a p27-luciferase (p27Luc) fusion protein and show here that its abundance, like that of p27, is regulated by Skp2 in a cell cycle−dependent manner. As predicted, p27Luc levels increased after blocking Cdk2 activity with inhibitory proteins, peptides or small interfering RNA (siRNA). Accumulation of p27Luc in response to Cdk2 inhibitory drugs (flavopiridol and R-roscovitine) was demonstrable in human tumor cells in vivo using noninvasive bioluminescent imaging. In theory, the approach described here could be used to develop bioluminescent reporters for any drug target that directly or indirectly affects the turnover of a ubiquitin ligase substrate.
    Original languageEnglish
    Pages (from-to)643-648
    Number of pages6
    JournalNature Medicine
    Issue number6
    Publication statusPublished - May 2004


    • Cyclin-dependent kinases


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